Control system



1,411,042. I q PatentedMaf.28,1 922.

E. S. LAMMERS, JR.

'CONTROL SYSTEM.

APPLICATION FILED MAR- 8.1919

WITNESSES: WVENTOR Edw/h SLam/mmdn ATTORNEY a specification were;sums tme OF ER Enwm's rum-ms, 3a., or yvmrmsnunc, rnnnsirnvnvre, AssIGuoa 'rowEs'rme- Housn- ELECTRIC & mumc'rumue couramr, A conronarron or PENNSYL-To all whom it may mm.-

1 Be it known that I,ED\;VIN SZ. Learners, x'Jr.-, acitizen ofthe UnitedStates, audaresident of Wilkinsburg, in the countyof Allegheny and Stateof Pennsylvania, have invented anew and useful Improvement in ControlSystems,-.of"which-.the following is My invention relates to electricalsystems and particularly to such systems as-are'em the control ofdynamo-electric Though my invention is of general appli- -cation,-it isof particular value in connection with systems embodying 'motors andgenerators. which are connected in circuit and is an improvement upon asystem forming the subject-m'atter'of my 00- nding application, SerialNo. 281525; led March 20 c1919.. One object of my invention isto providea a control system for a motor and a generator connected in a closedcircuit in which" the same resistors may be employed for acceler atingand decelerating purposes and-for au-. tomatic control in accordancewith circuit conditions.

A second-"object of my invention is to i provide a system of the.above-described i crater-field strength may be controlled by characterwhich shall employ a'minimum number of switches.

A further'object of my invention'is to provide such a control systemwhich shall'be adapted for troller. y t. Another object of my inventionis'to arrange the circuits in novel fashion as to. prevent reversal ofthe machines until circuit' conditions make such change desirable. Stillanother object of my. invention ism provide such a' system in which thegena resistor which is normally shortrcircuited i t decrease the timeelement required for ,ac'celeration purposes and which may be m :sertedinto circuit toweaken the field strength and to regulate the generatorupon the generator volt-age reaching .a' predetermined value. p a I;According to the present 1nvent1on, the

armatures of the generators and the motors are connected in a closedcircult, the field- -magnet windings of the several .machines control bya three-point con-' specification otLetters Yatent. Patented M81. 1922.Application fi led larch 8, 1919. Serial No. SIS 1,527 I v i beingseparably [connected a a source of energy, each in ser es with aresistor. The

motor-field-magnetwindings are perma connected to a source of constantvoltage, and the, .generator-field-magnet nently windingsmay connectedto thatsource byreversing switches when the master controlleroccupiesthe first of three operative positions. The Y composed of two portions,one of whieh a resistor, is normally generator-field resistor issoecalled permanent short-circuited in order to decrease the time lagrequired for accelerating the generator,

the short-circuit being adapted to be removed upon the voltage of thegenerator exceeding a predetermined value, or under other desirablepredetermined conditions.

traversing-the circuit of the armatures for regulating purposes. the,master controller'is adapted 'to open a short-circuit forthe motor-fieldresistor inorder further to accelerate the motor.

[Inlitsthird position, I

In the"circuit ofithe generator field-mag-i switchesione offihich isadapted to maintain energ zed thecircui't of the actuating coil of eachnofjthe reversing switches in orderto I =prevent1the premature openingof these re-f i-flnd them-e Pr vent reversal, until the generator 'fiestrength falls to apredetermined value and the other of net winding area tpair of actuating coils for Y which pair of switches is adapted to[control the"motor-field-resistor'switch? In the circuit of the motorfield-magnet winding is inserted an actuating 'coil for a switch whichisada'pted to control the generatorv resistor switch. A plurality ofswitches having acare provided for controlling the "resistor duringdeceleration.- 7 u The single figure of-the accompanying drawing is adiagrammaticrepresentation tuating coils controlled in accordance withthe current conditions of the"main';circuiti 1.00,

.40 of the motor by means of resistors 40 and of circuits and apparatusillustrating my invention.

A generator G anda motor M have'ar-- matures connected in series. Inpractice, a

plurality of generators and a plurality of motors are provided, as inthe-case of my above-mentioned application, the armatures of thegenerators and. the motors being disposed alternately in the circuit. Inorder the more clearly to illustrate my invention, I have simplified thedrawing by eliminating several of the machines.

, The motor M is provided with a separately'excited field-magnet winding41 and the generator G with a separately excited field-magnet winding44. In practice, the motor M will be' provided also with variablepotential field-magnet windings energized" by anexciter, as isillustrated in my abovementioned' application.

A resistor, sections of which are designated 21 and 40, is in serieswith the motor field-magnet winding 41, the resistor portion beingcontrolled by an electromagnetic switch 26, which is normally closed bygravity, though it may be designed so as to be closedelectromagnetically. A res1stor,

. 'cornposed'of two sections 13 and'43,is connected in series with thegenerator fieldmagnet winding 44, the section 13 being controlled by anelectromagnetic switch 12,

which is normally closed, and the portion 40 being controlled by anelectromagneticswitch 14, Additional resistors may, of

course, be included in the circuits both of the motor field-magnetwinding 41' and the 3 and generator field-magnet winding 44, whichresistors may .be controlled in any desired way. One of-the main objectsof my invention, however, is to effect the acceleration 43 only, eachcontrolled by. a single switch,

' 26 and 14, respectively.

The direction of the current traversing the generator field-magnetwinding 44 is controll d by electromagnetic switches. 1, 2,

4 I have illustrated the switches 1 and 3," as also the switches 2 and4,,-as

mechanicallyconnected. together and controlled by asingle actuatingcoil. In practice, as in my above-mentioned application,

the switches 1, 2, 3 and 4 are separate.

.A master controller 45, is provided, having three direct and threereverse operative ositions, a, b anda, in the first of which it controlsthe circuit of the actuating coil of the 'reversing switches '1 and 3 9r2 and '4, in the second of which it controls the switch 14, and in thethird of which it controls the switch 26. In the first position,therefore, the circuit of the field-magnet winding 44 is closed, in thesecond, the resistor 43 is short-circuited to increase the.

excitation of the generator field-magnet winding 44, and in the third,the resistor. 40;

.the said relays are connected to the line conductor by the relay 61.

versing switches 1 and..3, and 2 and 4,

respectively, whenv the relay 68, which has an'wactuating coil incircuit with the fieldmagnet winding 44, is closed. The relay 68 shouldbe designed so as to be closed at a very small current value; Theactuating coil of the relay 68 may, if desired, be con-- nected acrossthe terminals of the generator armature, or in any other equivalent way,so as to insure that, after the .reversing switches'have been closed,they will be maintained closed until the motor speed falls to 'a verylow value.

The switches 64 and 67 control the cir cuit of the actuating coil of theswitch 14 and the switches and 66 that of the actuating coil of theswitch 26, sothat not until the reversing switches have been closed canthe actuating coils of the switches 14 and 26 be energized. 'Theactuating coil of the'switch 14 is controlled by a relay 54 and b arelay 20, the latter of which is provi ed with an actuating coil incircuit with the "field-magnet windin' 41. actuating coil of the switch26 is controlled by "a relay 59 and a relay 32, the latter of which isprovided with an actuatin' coil in circuit with the field-magnet win ing44.

The relays 20 and 32 are, what I have.

termed in myabove-mentioned application, held-1nterlocking relays andshould preferably be connected, as in the said application, in parallelto the field-discharge resistors (not illustrated): The relays 54 and59, as also a relay 61, are provided with coils 55, 60 and63,respectively, which are connected across the terminals of one of thegenerator or motor-compensating windings 58. The relay 61 is providedalso with a shunt coil 62, which is so wound as normally to oppose thecoil 63, but which will The aid the coil 63 during deceleration. Duringacceleration, therefore, the relay 6i willremain in its open position;during deceleration, it will be closed. The relays 54 and 59 areconnected to the positive line conductor through the switch 64 or theswitch 67 and the switch 65 or the switch 66, respectively, duringacceleration. During deceleration, positive Theswitch 12 is normallyclosed by an actuating coil, the circuit of which is con- .let us say,to the-,left' tothe position a ,The controller arm will thereupon make.con

45 a holding predetermined value, this circuit will being coil-57, whichis connects terminals of the generator armature. Whennected to thepositive andnegative-oonduc .tors throug'h a relay- 56 havln.anactuatthe fvoltageof the generator-builds up to a come opened tocause the :insertion, intov the circuit-of-"th'e field-magnet windings44,

e of the resistor portion 13.; This resistor; portion 13, therefore,-serves a double puri pose, namely, to initially force the field neratorand to regulate the g'enerad excitation in accordance with the '30 cuitof 'thefield magnet winding 44 fwillj 'comprise'the resistor 43 ,but'theresi'storl 13 will-be 'short-oircuited because the ac}; tuating coilfofthe switch 12 ismaintained 3.5 energized by a circuit which extends frome ative ,line conductor.

negative? line conductor;

- drive the moto'r'in one direction.

of the tor-fiel value of the voltage of the generator.

In operation,i the controller 45 isactuated,

tact with a contact member 42, whereupon a circuit will be establishedfromthe posi-j tiveline conductor by way of a' condu'ctor- 16,throughthe controller "arm 45, the contact member 42, the switch 51 andthe ac-- .tuating coil of "the'switches 2 and 4. to the The. reversingswitches 2'andf 4 will thereuponclosed to establish the circuit ofthefield-magnet windings-44 for operation of the generator with a certainpolarity. Thecircuitofthe shuntzcoil-62 will also be energized by theclosing of the reversingswitches. The cirthe positive line .conductor,rby way of. condueto'rsilfi and 17 {through the relay-56 and theactuating coil-'ofthe'switch12, to the en the current traversing thecircuit of the fieldmagnet winding 44 rises to a predetermined,-

small value, i the. actuating coil of the relay 68 will close-the relay,thereby establishing circuit for :the actuatin .coil of the reversingswitches 2'and'4, this circuit extending from the positive lineconductor,

- by we ,of conductors'.16, 1Z and 18, through the 'reay 68, the switch70 and the actuat ing coil of the, 'rev'er'sin switches'2 and '4,

to the ne ative'line con uctor. ,ZThe reversing'switc es 2 and'4 will.now -be maintained closed, irrespective ofythefposition of thecontroller 45,. until the currents-traversing r the field-ma 'et winding44 falls to avalue" sufliciently 'ow to oftherelay68. r v a The relay68must be so designed asnot to operate when the ;master switch .45 isfirst actuatedto the position a. If the relaywereto operate at atimewhenthe resistor permit of the opening a 43 is in circuitwith the'winding44,itco'uld never open so long as'the wind ng remained energized, becausethe lowest current Ivalue' across the I I. lia lit. Thegeneratorwill-thereu on o crate-L would prevent reversal.- The relay '68 shouldwould obtain at 'suchtime, This/of course operate at a low currentvalue, but. only- .after' the resistor 43 has become short-circuited. A

The controller '45 -may 'now'b e actuated to the positional), so as toengage the conjupon operate to short-circuit the, resistor section 43-and thus'increase the field-excitation' of the generator. Theshort-circuit ing ofthe resistor section 43 causes the voltage of thegenerator G to assume a corresponding value,- and the motor M will beac-" celerated to a corresponding degree. If the current traversing themain circuit, comp'risin the motor M and the generator G,

willbe energized 'suificiently to cause the opening ofthe' relay-54 andtheconsequent opening of the circuit of the actuating coil of the switch14, whereupon the resistor vsection 43 will be reinserted intofuthe circuit to decreasethe excitation of the generator field-magnet winding44,The relay 54 will flutter-- to cause the alternate closing and opening.of the switch 14 until the volt- .age; ofthe generator G builds up tonormal value. The same I resistor 43', therefore, serves 1 the doublepurpose of accelerating .ex'cees a predetermined value, the coil 55 thegenerator, and regulating its speed in accordance with the currenttrave'rsingits When the controller is actuated to its third position c,to engage a contact member '75, av'c'1rcuit will be establishedfromthepositive linecond'ucto'r, by. Wayvof the conductor'16, throu h. thecontroller arm 45, the contact member ifi, the switch 66, the relays '59and 32 and the actuating coil o'f the switch 26, to the n egativ'e lineconductor. The I switch 26 will-thereupon be opened to insert theresistor section 40 into circuit with the field-magnet winding 41,thereb ".to cause further. acceleration of the motor Asthe circui-t ofthe actuating coil of the'switch 26" i is controllediby the fieldinterlocking relay 32, the switch'26'ca'nnot be opened until the"current traversing thege'nera'tor field-magnet winding 44 reachesa-val'ue high enough to cause the closing of the relay 32, so that incase the controller arm 45 is actuated, not

.step-hy-step, as above described, but to'the positioucyin one step,there will be no danger of the switch 26 opening prematurely before thefield-magnet winding 44-has been excited to normal value. Inpractice,the

controller arm 45 will be actuated by a rapid movement tosits finalposition c.

iii the current traversing the circuit of the armatures of the motor Mand-the generator (-iexce'ds a. predetermined value, during the furtheracceleration of the motor, the relay 59 will be actuated by its c oil60to break the circuit of the actuating coil of the switch 26,

- permitting the switch 26to -be reclosed by gravity and the resistorsection 40 to be" again short-circuited. The v relay 5?} will flutter-toc'au'se the opening and the closing of the switch 26 in accordance withthe value of thelcurrent traversing the. circuit of the motor andthegenerator armatures, so that the single'jswitch 26 will.serve' not onlyfor the' purpose of accelerating themotor M, but

also tolregulate its speed in'a'c'cordance'with the when traversing the:circuit. of the motor f and 1" generator armatures.

The'lnotor M will now operate at its nor- .mal operating speed, with thegenerator voltage at a normalvalue and the'motor field weakened toanormal degree. If, at any time during; normal operation, the currenttraversing the main circuit exceeds a predetermined -value, the, relays54 and 59 will operate," in the manner described, in connection withthedescriptionof the process of' acceleration, to control the I resistorsections-43 and and thus to maintain the current traversing the maincircuit within predeterminedlilnits; 1

The enerator 'Gis usually a, fly-w eel set. When the 0 driven from adupon the motor M is heavy, the'fiy-wheel' is made-to release its energythrough a slipregulator which is connected in the secon ary circuit ofamain induction motor, which drives the generator Gr. If the'load issustained for any appreciable length of time,.the speed of the fiy-wheelset is considerably reduced as the fly-wheel releases its energy, andthe generator. voltage is thereby accordingly reduced," which not onlyaffects the speed of the motor M but also the power-that can be suppliedto it. The generator voltage, furthermore, has a tendency to becomereduced underheavy loads, due to the inherent voltage'characteristic ofthe generator; 1 provide for this difliculty b'yinsuring the inser tionof the additional resistor section 13 into circuit with the field-magnetwinding 44, upon the generator voltage exceeding a predetermined limit,through the '0 ning of the switch 12, by the breaking of t e circuit ofits actuating coil by ,thedelay 56, the

actuating coil57 of whichisg responsive to the voltage of the generator..When the voltage of the generator becomes decreased from any'causes, asthose above referred to, the coil 57 will not be able to maintain therelay 56 in its open position',whereupon the relay 56 will be closedjbygravity to cause again the energization of the actuating coil of theswitch 12, the consequent. closing of this switch 12 and the resultingshort-circultiugofthe resistor portion 13, in order to increase theexcitation of the field-magnet winding 44. The switch 12, like theswitches 14 and "26,,may thus flutter in accordance with theielectrifcalconditions of the machine, the switches 14 and 26' being responsive tocurrent conditions and the switch 12 to voltage conditions.

- The resistor section 13 thus'plays a double L function, namely, as'itis normally shortcircuited, serves initially to allow the overexcitation .of thegenerator field-magnet winding 44, so as to reduce thetime interval necessary to bring the excitation of this\v'indingtojnormal value and, secondly, it serves. to regulate theexcitation of the windingfi'n accordance with the value of the voltageof the generator,

' Vhen it :is .desired 'to stop the motor, the.

controller arm is actuated toward its off position. The motor M thenoperates as a generator when the elec-tromotive"force generated by itexceeds the voltage of the generator The current now traverses thecircuit of the armzitures-in the reverse direction so that the coil 63will aid the coil 62. The relay 61 will accordingly 'be'actuated to itsupper position, to establish a'circuit from the positive line conductor,by way of conductors 16 and 19, to the relayfil and from there to eachof th'erelays 54 and 59. f The relays 54 and 59 will now respectivelycontrolthe switches 14- and '26 when they.

serve not only for accelerating the motor, but also for deceleratingpurposes and for regulating the speed of the motor both durinacceleration and deceleration. when it is desired to operate the motorsin the opposite direction, the cont-roller 45 may be' actuated to theright. This actuation may be effected step-by-step or by one rapidmovement from the extremejpositiontc, corresponding tooperation in onedirection. to the extreme position 0 cor'respondin 'to operation in thereverse direction' he circuits of the actuating coils of the switches 14and 26 are immediately opened at the contact members 81 and 75, but. thecontrol of the switches transferred, as just described in'connectionwith the description of the operation of bringing the motor to rest,

to the relay 61. Not untilthe speed of the motor falls to a.sufliciently low value and the excitation of the generator field-magnetwinding 44becomes sufficiently reduced to causetheopening of the relay68, however, can the reversing switches 2and 4 be opened.

- The reversing switches I and-3 cannot be 14 during deceleration. Thecontrol circuit may be traced from the positive line conducr tor,.by wayof'conductors 16, 17 and 15 closed until the switch 46 assumes itsnormal position following the opening of the switches 2 and. 4.- Notuntil .the reversing switchesl and 3 are closed-can the actuatin coilsof the switches 14 and 26 be controlled through the relays 20 and 54 andthe actuating coilof the switch 14, to thenegative line conductor; Thepermanent reopening of the switch l4-to cause the reinsertion, into the"circuit of the fieldmagnet winding 44, oi the resistor 43 isthusprevented until the switch 26 has'becom'e permanently c'lpsed by gravityto increase the excitation of the field magnet; winding 41 to a degreesufiicient to causethe permanent' closing ofthe relay 20.

WVhen the generator voltagehas become reduced to a sufficiently lowvalue, the relay 68 will be opened, the reversin switches 2 and 4 willthereu on be open ,1! the reversin-g 1, an 3 will become closed, and theacceleration of the motor in the reverse direction wilI-take'place in amanner s'uh-' ntially the same as that above.

wish it to bGlllIldBIStOOd that the disclosed embodiment of myinventionisrillus trative purely. Many details necessary for thepractical operation of the system' have -been omitted, inorder tosimplify the .drawh g8, I desire that fmy inventionlbe construed asbroadly as ;.ind1cated in the annexed 'said machihe, of P 1 f swit h vpectively' controlling th opemhon Sald,

controlling switch during the accelerationclaims] a I claim 1 as my.inventlon I r I 1. Th combination witha; dynam elec tric machine and aswitch for controlling torre- I andthe deceleration'of said machine.

hamo-eletric machines-having -s1stors respectively-1 assoclatetherewith, a

'apair of renormally open 7 single switch ior' ',short cir'-= cuitingone of said-resistorsganda normallyclosed singleswitch for shortcircuitin said other resistor,' ofmeans for 'closing'sai nor- 'ma-llyopen-swltch to accelerate one of sald machines, means for opening sa dnormally a resistor in circuit therewith, of a switch for controllingeach of said resistors, each of said .revcrsingswitches for re I thirdvosition.

-' v7.-. he Combination. dy a o 1 "a 'Witchfor closing the closed switchwhen the current traversing saidone machineexceeds a predetermine valueand means for alternately opening and closing both of; said switchesunder predetermined conditions. i

3. The combination with generator having armatures connected in seriesand field-magnet windings each. having a resistor -in circuit therewith,of a i switch for controlling'eachof said resistors anda pair ofswitches having actuating coils in circuit with saidarmaturesforrespectively controlling said controlling switches.

4. The combination "with a motor and agenerator havingarmaturesgcon'nected in series and. field-magnet windings each having aresistor in circuittherewith, of a switch 'for controlling each of saidresistors and a pair-of switches having actuating coils in' circuit withsaid armatures for resectively controlling said controlling switches.

5. The. combination" with "a motor and a generator having all-maturesconnected in series and field-magnet windings each having havinganactuating coil, a pair' of switchesv having actuating coils inc1rcuit-with. .said I armatures for respectively controlling thecircuits of said first-named coils, a pair of switches for reversing thedirection of ourrent flow in said generator windin a pair of switchesmechanically connecte to each' controlling each" of said first-namedcoils during acceleration and'a switch for control spectively v a motorand a ling both of said firsteinamed coils during? deceleratioii.

6. The comb-mandates smear, the} generator having field inagnet windingsand resistors in circuit therewith, ofathrecpoint controller andmeansyfor closing the circuit of said generator field-magnet, windingwhen said controller occupies one of-its positions, for ;controll' oneof Qaidfre- 1 sistors when "said contro er- 0cc ies sa'sec-.

end position jand'for controllin'g said other resistor when saidcontrollei 'occupies a 8. The combination-with ai 'dynamoelem $1 20 triomachine and a; switch .for closing the 2. Thej co'mbination.with apairof 'dy-' ating coil, of a second switch'f r' 'controlling rthe.energizatio'n of said coil said second switch having' an act cuit ofsaid'ma'chine 9., The combination, as

other machine, and means responsive to the I current traversing thearmature of'one of said machines for rendering said controlling meansineffective:

. and current-responsive means for regulating i the voltage of saidgenerator during the normal operation of said motor.

1 1. The combination with a dynamo-electric machine having-a resistor intwo sections associated therewith and a single switch for shunting oneof said sections, of means for alternately closing and opening saidswitch according as'the value of the current traversing said machinefalls below or exceeds a predetermined value, a switch for normallyshunting said other section, and means for controlling said last-namedvoltage of said machine.

12. The combination with .a dynamo-electric machine having a resistorassociated therewith, of means for inserting a portion of said resistorinto circuit when the current traversin said machine exceeds apredetermined va ue, and means for short-oil's cuiting a portion of saidresistor when the voltage of said machine falls below a predeterminedvalue. v

- In testimony whereof, I have hereunto subsciihed my name this 26 dayof Feb. 1919.

EDWIN iQAMMERs, JRQ

switch in accordance with the value of the

